Impact of accelerated aging of <scp>epoxy‐Ni</scp> nanocomposites on space charge variation adopting pulsed electro acoustic technique

Huang

ACS Appl. Mater. Interfaces

et al. 2022

Gamma radiolysis behaviors and mechanisms of silica-filled o-cresol formaldehyde epoxy are studied at 2.20 × 10 −5 to 1.95 × 10 −1 Gy/s. The radiolysis-induced changes in chemical structures do not severely affect its thermostability. The slightly deteriorated mechanical strength at temperature exceeding 100 °C is accompanied by the declining glass transition temperature (from 185.9 to 172.2 °C) and enhanced damping ability. The gas yields of hydrogen, methane, and carbon dioxide manifest a remarkable dose rate effect. Based on the Schwarzschild law, their yields at an extremely low dose rate are accurately predicted by the established master curves. Besides, the latent radiolysis of gas products and postradiation effect are found with caution. The radiation-caused residual spin species are proved to be composed of silica defects and a phenoxy-type free radical with a tert-butyl group, according to the experimental results, theoretical calculations, and spectra simulations. The lower vertical ionization potential (7.6 eV) and adiabatic ionization potential (7.1 eV) are primarily due to the ionization of the benzene ring moiety with the tert-butyl group, which is likely to suffer from radiolysis. The calculated bond dissociation energy (260.8−563.5 kJ/mol) of the typical chemical bonds of epoxy is consistent with its radiolytic vulnerability and degradation mechanisms.

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Study of Gamma Radiolysis and Dose Rate Effect of o-Cresol Formaldehyde Epoxy Composites

Huang

ACS Appl. Mater. Interfaces

et al. 2022

“…As a thermoset matrix for advanced engineering composites, epoxy resin (EP) exhibits a range of excellent properties, including high tensile strength, excellent dimensional stability, and good chemical resistance. [1][2][3] Today, EP materials are widely used in automotive, aviation, rail transportation, and construction. [4][5][6][7] However, neat EP suffers a lot from its brittleness, fatigue resistance, and poor tribology behavior.…”

Section: Introductionmentioning

confidence: 99%

Interfacial tailoring of basalt fiber/epoxy composites by metal–organic framework based oil containers for promoting its mechanical and tribological properties

Pan

et al. 2023

Polymer Composites

The chemical inertness of the basalt felt (BF) results in a weak interface bonding between BF and polymer matrix, which hinders the further application of BF reinforced composites. In this study, nickel‐based metal–organic framework (Ni‐MOF) sheets were decorated on the surface of BF by a facile one‐step hydrothermal method to improve the interfacial bonding between BF and epoxy resin (EP) matrix and embed solid paraffin. The mechanical and tribological properties of EP composites reinforced with BF were evaluated. The interfacial shear strength (IFSS) between BF and EP was measured by a single‐fiber drawing test, and the results indicated that the IFSS increased by 15.19% after MOF modification. The surface of BF transformed from hydrophilicity to hydrophobicity, therefore significantly improving the compatibility between EP and BF. Compared with pure EP, the composites exhibited improvements of 37.55% and 203.39% in tensile strength and tensile modulus, respectively. Meanwhile, the friction coefficient and specific wear rate of the composite decreased by 58.82% and 56.50%, respectively. The solid paraffin was observed to be enclosed by Ni‐MOF sheets, which endowed the composite with a self‐lubricating behavior during friction. This study will advance the comprehensive performance of EP and provide a versatile strategy for tuning the interface compatibility between the reinforcement material and the matrix. Highlights A novel Ni‐MOF decorated BF was developed for storage of PW. The BF/MOF/PW can simultaneously boost the tribological and mechanical properties of EP. Surface tailoring of BF was realized with decorating MOF sheets and embedding PW. A decline in friction coefficient by 58.82% was achieved.

Space Charge Behavior in Epoxy‐Based Dielectrics: Progress and Perspective

Xie

et al. 2022

Adv Elect Materials

temperature and complex electric field conditions. [1][2][3] Epoxy resin (EP) is a class of polymer oligomers containing two or more epoxide groups based on organic compounds (e.g., aliphatic, alicyclic, and aromatic). As a prepolymer, EP shows excellent performance after its reaction with a curing agent to form an insoluble polymer with a 3D network structure. EP has desirable insulating characteristics, [4][5][6][7] heat resistance, [8] high mechanical strength, [9] low shrinkage, [10] chemical stability, and adhesive properties, which originate from its compact structure and tunable functional groups. The above mentioned outstanding performances, along with characteristics of easy processing and formula design flexibility, enable the extensive use of EP-based materials in power equipment and electronic devices [11] (Figure 1), including bar insulation and impregnating varnish in transformers, main insulation in dry-type bushings and wall bushings, insulator in gas-insulated switchgear (GIS) and gas-insulated transmission line (GIL), epoxy molding compound for integrated circuit (IC) packaging. It is noteworthy that EPs typically possess lower glass transition temperature (T g ) compared to other high-T g dielectric polymer substitutes used in microelectronic systems such as benzocyclobutene, [12] polyimide (PI), [13] and maleimide. [14] Besides high T g , high thermal conductivity and low coefficient of thermal expansion of EPs are always desired for their industrial applications, especially from an electronic packaging perspective. To date, considerable efforts have been made to improve the heat endurance and heat dissipation capabilities of EP-based dielectric materials by inorganic particle doping [15][16][17][18][19][20][21][22][23][24] and chemical modification. [25][26][27] Furthermore, EP is also an indispensable adhesive that is extensively used in power equipment. [28][29][30][31][32] Yet, potential reliability hazards may exist during the operation of power equipment and electronic devices, especially at high temperatures and under high voltage direct current (HVDC) application, one of which is the space charge accumulation in EP-based dielectric materials. [29,30,33,34] The accumulated space charge may cause deterioration/aging and even partial discharge or dielectric breakdown of dielectric materials. [35][36][37][38][39][40] Specifically, the extensive application of EP-based dielectric materials in HVDC transmission projects eagerly calls for relevant studies on the space charge behavior Epoxy-based dielectrics are extensively used in grid-connected energy systems and modern microelectronics as electrical insulation, adhesive, and packaging components. However, space charge accumulation in epoxy-based dielectrics is a foremost factor threatening device stability and lifespan, especially under conditions of high voltage direct current and high temperatures during long-term operation, and thus are investigated systematically. This article reviews the state-of-the-art progress in understanding and r...